The present invention relates to a vacuum pump or ejector, which is used for generating a negative pressure in a medium used for transportation or lifting, e.g., and more particularly to a vacuum pump having a nozzle body with at least one integrated valve member.
Pumps for generating a vacuum using overpressure are known in the art, see for example FIGS. 1a-1d of the appended drawings. Ejectors of the intended type, so called multistage ejectors, usually comprise two or more nozzles arranged in series within a house, wherein a surrounding space such as a chamber is associated to each respective nozzle, which extends through the partition wall between adjacent chambers. The nozzles present a through-channel with gradually increasing, sectional opening area, through which a stream of air with high velocity is fed to carry, through a slot located between the nozzles, air or other medium in the surrounding chamber and generate therein a lowering of the pressure.
When three or more nozzles are coupled in a series, the respective chamber is commonly in flow communication with a common or outer space, which has coupling means for connecting the vacuum pump to external equipment. A non-return valve in the form of e.g. a flexible tongue is arranged in the flow path to prevent leakage between the outer space and that chamber which, upon a certain difference in pressure, ceases to be active for further lowering of the pressure.
Ejectors of this known construction may be formed with nozzles coupled in series, with different efficiency characteristics in order to provide both a high vacuum flow and a low vacuum level in one ejector.
It is the object of the invention to provide an improved ejector of the above type, which permits greater flexibility and freedom of choice when built in with equipment for different applications wherein a space is to be evacuated or vacuum to be used for transportation or lifting. The ejector according to the invention also permits simplified assembly and disassembly in service and maintenance.